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基于近年来多次野外洪枯季沙波形态、河床表层沉积物粒径和水动力因子等方面实测数据,探讨长江口区推移质泥沙运动主要形式的沙波发育规律。结果表明:(1)长江河口沙波一般分布于江阴至南支间顺直河段,以及吴淞口至南港中下段区间,但近年来枯季时南港沙波发育区域呈逐年向下游扩展态势;(2)长江口沙波发育尺度空间上呈自西向东减弱态势,时间上则表现出较大的洪枯季差异;(3)江阴至南支区间的部分顺直河段内多发育较大尺度的三维沙波,而南港河段内沙波则以平直二维沙波为主;(4)南支及其以上河段内的沙波普遍发育有明显的背流面,不对称性明显,而南港河段则反之,沙波对称性良好;(5)较单向径流而言,涨落潮双向水流对沙波波峰的发育存在明显的削弱作用;(6)在长江河口,弱流乱流区、弯曲河道以及粘土质含量较高的河段均不利于沙波的发育。总体上,长江河口沙波的发育区域近期表现出向下游扩展的态势与产流区域水土保持、流域诸多抽引水工程调水和大型水利工程蓄水等有关。
Abstract：Field measurements of bedforms,bed sediments and tidal currents were made in the Changjiang estuary,China,during December 3-5,1997;September 8-10,1998;March 28-30,2002;February 22-23,2006 and 20th August 2006.Results show that subaqueous dunes mainly distribute in the straight channels from Jiangyin to the South Branch,and the river channel from Wusong to the downstream of the South Channel with a lower limit of 121°44.570′E in the Changjiang estuary;the regime termination of dunes in the Changjiang estuary has put up a expanding trend toward downstream direction during dry seasons in the South Channel,with a migration of 11.7km in the recent four years;the scale of dunes in dry seasons is extremely smaller than that in flood seasons,and the main feature of dunes is consist of 3D dunes during flood seasons,while 2D dunes have a dominant statistical status in dry seasons.Low velocity and circular flow conditions,curving channels and high-clay-content bedload conditions have bad effect to sandwave growth in the Yangtze estuary.It is clearly that rapid decreasing of sediment flux caused by water reservoirs especially the Three Gorges Reservoir plays an important role in resulting dunes' regime expanding toward downstream in the South Channel in dry seasons.
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基本信息:
DOI：10.16239/j.cnki.0468-155x.2008.06.001
中图分类号:P737.14
引用信息:
[1]李为华,李九发,程和琴,等.近期长江河口沙波发育规律研究[J].泥沙研究,2008(06):45-51.DOI:10.16239/j.cnki.0468-155x.2008.06.001.
基金信息:
国家自然科学基金资助项目(40776056,40576048)
2008-12-15
2008-12-15